Heat exchanger



AP 1-3, l io w, w, KENNEDY HEAT EXCHANGER Filed June 17, 1944 2 Sheets-Sheet 1 3/ 4 w 12 l9 E llli I INVENTOR Walt er M Kennedy A ril 13, 1948. w. w. KENNEDJY HEAT EXCHANGER v ma ma Filed June 17, 1944 2 Sheets-Sheet 2 41.1. m H F I 8 v I r m llllili j 2 M Rm n O N m m EM n w A r e M %m wfi v4 4 M m. 3 5 II. J 1| w.. If

Patented Apr. 13, 1948 2,439,715 naa'r axcnaneaa Walter W. Kennedy, Rockford, Hit, assignor to Barber-Colman Company, Rockford, Ill., a corporation of lllinois Application June 17, 1944, Serial No. 540,843

1 (liaim.

distributing grille and heat exchange coil of advantageous character capable of increasing the heat transferring capacity of the device when used in association with an air impelling fan oi'the axial thrust type.

Another object is to provide an improved heat exchanger in combination with an axial thrust fan in which the fan is disposed within a casin having a laterally disposed air inlet in upstream relation thereto together with means for distributing the air radially of the fan blades while forming a heat exchange coil imposing a minimum of resistance to the flow of air in its passage transversely into the casing and thence axially for discharge from the casing.

The invention thus generally characterized is susceptible oi various practical applications among which is the cooling of the transmission oil in armored tanks employing hydraulic transmissions. With this in view, the invention has for another object the provision of a combined air distributing grille and heat exchange coil for tanks and the like functioning not only to increase substantially the volume of air impelled through the tank housing by the cooling fan but also constituting a heat exchanger capable of extracting eifectually the heat of the transmission oil,

' Still another object is to provide a combined air distributor and heat exchange coil for tanks of the character set forth together with an advantageous thermostatic control for rendering the de- ,vice inoperative as a cooling unit when unneces sary or undesirable as, for example. during warming up periods.

Another object is to provide a space heatin device of the type commonly known as unit heaters, embodying my improved heat exchanger.

The objects of the invention thus generally stated, together with other and ancillary advantages, are attained by the construction and arrangement shown for purposes oi illustration in the accompanying drawings forming a part hereof, wherein blades.

Fig. l is a fragmentary sectional view or the rear portion of an 'armored tank and showin somewhat schematically the motor compartment with my improved heat exchanger in operative association with the motor in such compartment.

Fig. 2 is a cross sectional view through two adjacent cooling vanes and illustrating schematically the manner in which the cooling air entering transversely oi the housing through a laterally offset air inlet is turned and directed rearwardly into the fan.

Fig. 3 is a perspective view of a portion of one of the cooling. vanes.

Fig. 4 is a similar view of a modified form of vane.

Fig. 5 is a transverse sectional view taken approximately in' the plane of line 5-8 of Fig. 1 but on a larger scale and showing schematically the construction of the device as a heat exchange coil with inlet and outlet headers in association with an oil supply tank.

Fig, 6 is a fragmentary sectional view on an ening fan It in the forward portion of the motor compartment i2 of an armored vehicle such as a tank. The fan is mounted upon the shaft of the engine it, which is shown as of the radial cylinder type, .the power unit as a whole being disposed upon an axis positioned somewhat downwardly and forwardly in the usual way. A shroud l4 encircles the fan and forms together with an in tegral web it an annular fan casing having a forward .circular end portion it receiving the fan with slight clearance for the ends of the fan Air is admitted to the forward portion of the motor compartment through an air inlet l8 offset laterally of the fan casing, and is discharged from the rear portion of the tank through an air outlet opening downwardly as at ii.

In the embodiment of the invention shown in Figs. 1 to 6. the unit ill has two major functions. namely, that of an air distributing grille acting upon the air entering the tank housing through the laterally offset air inlet It to turn or direct it axially of the fan it while distributing it radially of the fan blades; and that of a heat exchange coll for "extracting heat from the transmission oil. Tothese ends, the unit comprises a series of concentric annular vanes II or gradually decreasing diameter and spaced apart radially as well as along the tan axis so as to form a frustoconical grille; and the vanes are made hollow and interconnected to form a coil arranged for the circulation of the transmission oil.

The specific construction employed may be substantially like that set forth in my copending application, Serial No. 492,567, filed June 28, 1943. In brief, the vanes I8 are supported in spaced relation by means of generally radial plates I9 apertured for the passage of the vanes. The in-- ner ends of the plates are secured to or rest upon an annular member or ring 20 encircling' the fan hub II in closely spaced relation thereto, the outer ends of the plates being suitably fastened to the shroud I4 as by means of lugs 2|. The ring 20 projects forwardly from the fan, its front edge coacting with the annular partition ring I4 to form an outwardly and forwardly facing air inlet opening closed" by the combination grille and coil of frusto-conical form.

The plates I9 are generally triangular in form with outwardly and rearwardly inclined edge portions in which the vanes are mounted; the rear edges of the plates terminating immediately adjacent the fan. Additionally, the plates serve as antiswirl devices. For this purpose they are inclined rather sharply relative to the plane of fan rotation so as to guide and direct the air somewhat diagonally of the axis of the fan and across the leading faces of the fan blades.

Referring now to Figs. 2 and 3 of the drawings, the annular vanes I8 are especially shaped so that not only do they perform the function of directing the laterally flowing body of air axially .in a series of concentric streams but accomplish this result in such a way as to minimize the pressure drop incident to the passage of air through the unit. To this end, the vanes are preferably of airfoil design with adjacent vanes forming between them curved passages gradually decreasing in radial width toward the point of discharge of the air streams from the unit. As a result, the air travels through the unit at high velocity, gradually increasing to the point of discharge. Moreover, the gradual decrease in the radial width of each passage insures an intimate scrubbing action of the air upon the walls of the passage formed by adjacent vanes, whereby to promote the transfer of heat from the vanes to the moving body of air.

As hereinbefore indicated, the air directing vanes are made hollow for heat exchange purposes, Thus, each of the vanes forms, in effect, a wide circular channel of relatively thin cross section for the conduction of the oil to be cooled. Moreover, the vanes may be equipped with a multiplicity of generally radial fins 22 to increase heat conduction from the vanes, said fins also co- I operating with the plates I 9 to restrain rotational movement of the air incident to the rotation of the fan.

To provide for the circulation of oil therethrough, the vanes are interrupted at one point in their circumference to accommodate headers 23 and 23'- (Fig. the ends of the vanes opening into the respective headers as shown in Fig. 6 so that the several vanes are connected in parallel. As herein shown, the header 23 constitutes the inlet header and oil is delivered thereto from a supply tank 24 by a pump 25 and pipe 25 The header 23, constituting the outlet header, discharges through a return pipe 26 back to the tank 24.

The supply tank 24 represents in the present instance a single source of fluid to be cooled. It will be understood, however, that the heat exchanger may, if desired, be divided into sections so as to serve as a cooling means for different fluids such as the ordinary lubricating oil for the engine of a tank, transmission or gear case 011, and the oil employed in a hydraulic transmission system or torque converter. In the latter case it'is especially important that cooling be provided. In the case of tanks, for example, the heating of the oil used in the torque converter, particularly when operating idly, is so great as to render the use of this type of transmission impractical. When the device is used for cooling lubricating oil, provision is made, as will presently be described, for by-passing the oil relative to the vanes I8 during warming up periods.

To insure uniformdistribution of the oil over the surfaces of the vanes I8, the latter are pref erably equipped with inner corrugated plates 21 coextensive with the vanes and forming with opposite walls of the vane contiguous channels 28 and 29 so that one channel is formed in part by one wall and the next adjacent channel by the other wall. By this arrangement, any tendency of the oil to be confined to one wall of the vane as distinguished from the other, or to limited portions of the vane is efi'ectually avoided. Instead of vanes of the design shownln Figs. 2 and 3, vanes 18' of teardrop contour, as shown in Fig. 4, may be employed. Distributor or breaker plates 21' within the vanes I8 would of course be shaped to conform to the modified cross sectional shape of the vane.

To provide for automatic control of circulation of oil through the heat exchange coil, one of the headers (herein the inlet header 28) embodies a thermostically controlled valve 30 (Fig. 6) in association with the annular by-pass channel SI of large capacity as compared to the vanes I8. This channel 3| is formed by a circular pipe opening into a compartment 82 of the header 23 but communicating with the latter through the medium of a port 83 normally closed by the valve 30. The opposite end of the pipe 3| opens into the opposite header 23.

The valve 36 is normally held closed by a temperature responsive element in the form of a bellows diaphragm 84 and the latter is preferably supported so that the valve may also serve when necessary as a relief valve. Thus the bellows is supported on a stem 35 having a head 36 yieldably urged by a spring 31 in a valve closing direction andagainst a stop provided herein by a stationary member 38. In normal operation, the thermal element 34 is filled with a suitable fluid responsive to the temperature of the oil. When the latter is cool, the bellows diaphragm will be contracted so as to open the valve and permit the circulation of the oil through the relatively large channel 3|. After the oil reaches a predetermined temperature rendering it desirable to extract heat therefrom, the valve 30 will move into position to close the port 33 so as to confine the circulation to the vanes I8 except in the event that the pressure exceeds a predetermined maximum whereupon the valve unit as a whole will yield as permitted by the spring 31, thereby permitting circulation through the by-pass channel 8|.

- As illustrated in Fig. mm invention may be effect a more uniform distribution of air lengthwise of the blades 38 of an axial thrust fan 39. Likewise, the vanes are made hollow for the conduction of the heating medium such as steam, the ends of the vane being connected to inlet and outlet headers 40 and 4| connected by pipes 42 and 43 to the heat source.

As shown, the fan 39 is mounted on the shaft 44 of an electric motor 45. The unit casing comprises a top plate 46 through which the fan shaftextends, the shaft having a suitable outboard bearing in a frame member 41 rigid with the top wall 46 of the casing. Additionally, the casing provides an annular shell or ring 48 encircling the fan 39. Between this ring 48 and the top plate 46 extend diagonal fins 49 apertured to receive the vanes l8 and maintain the same in proper spaced relation. The air inlet to the easing is formed between the top plate 46 and the ring 48 and it will be seen that as illustrated by the arrows the entering air is divided into a plurality of contiguous streams and directed axially into the fan.

It will of course be understood that the vanes ll of Fig. 7 are by preference of the contour and approximate spacing shown in Fig. 2, or alternatively, that of Fig. 4. As in the case of the air distributing and cooling device of Figs. 1 to 6, the coil serves efiectually to deliver and distribute the air entering laterally of the casing, radially relative to the fan blades so as to utilize the fan to maximum advantage in impelling air through the coil. And not only is the air moved at high velocity over the vanes but it passes over the surfaces of the vanes in intimate scrubbing relation thereto, thereby increasing the heat exchange relation between the vanes and the moving body of air. I

I claim as my invention: 1 A combined air distributing and heat exchange unit comprising, in combination with an axial thrust fan, a. plurality of hollow annular air distributing vanes of uniform cross sectional area disposed forwardly of the fan and spaced apart equidistantly along the axis of the fan as well as radially therefrom to form the frustum of a cone, said vanes being of airfoil section and bent transversely so as to act upon air entering between the vanes substantially radially of the coil to turn it axially while distributing it over and along each of the fan blades, and means interconnecting the vanes and providing an inlet and an outlet for a fluid medium.

WALTER W. KENNEDY.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS France July 24, 193'! 

